Drive chain



H. S. PIERCE vDRIVE CHAIN Feb. 2, 1937.

Filed April 27, 1931 5 Sheets-Sheet l EM V W d m ff/ r \\V\ A r x Feb. 2, 1937. H. s. PIERCE 2,069,591

DRIVE CHAIN l Filed April 27. 1951 5 Sheets-Sheet 2 H. s. PIERCE 2,069,591 Y.

DRIVE CHAIN Y Feb. 2, 1937.

5 sheets-sheet 4l Filed April 27. 1951 H. S. PIERCE DRIVE CHAIN F eb. 2, 1937.

5 sheets-sheet 5 Filed April 27, 1931 X72 vena @Z Faeroe /ttorRLeg/S Patented Feb. 2, 1937 UNETED STATES DRIVE CHAIN Harold S. Pierce, Indianapolis, Ind., assigner to Link Belt Company, Chicago, Ill., a corporation of Illinois Application April 27, 1931, Serial No. 533,146

9 Claims.

My invention relates to improvements in drive chains and has for one object to provide a new and improved chain wherein thrash or lateral vibration is reduced to a minimum. Another object is to provide as an essential result of the chain design, yielding means which inevitably and automatically produce an immediate effect upon the chain to resist from its inception any tendency towards movement of the chain between the sprockets over which it travels, along lines perpendicular to its path of travel. Another object is to so arrange and form the chain as to provide means which supplement the aforesaid resisting means to positively stop chain deflection beyond a certain predetermined limit. Another object is to provide a chain wherein a materially increased bearing and load supporting surface is available during the time when the chain is not deflected while at the same time providing a chain whose irictional resistance to deflection as it winds onto or off of a sprocket is reduced to a minimum. Other objects will appear from time to time in the specification and claims.

My invention is illustrated more or less diagrammatically in the accompanying drawings, wherein- Figure l is a side elevation of a piece of chain showing some of the pintle pins in section.

Figure 2. is a plan view of the chain of Fig. 1 showing some of the links in whole or in part in section.

Figure 3 is a side elevation on an enlarged scale of two of the links shown in Fig. 1, the pintle pin in section, the links in the position they would assume with the chain subjected to straight line tension only.

Figure 4 is a View similar to Fig. 3 but with the parts in the position of maximum front bend with the positive stop means effective.

Figure 5 is a similar view to Fig. 3 with the links at the position of maximum back bend.

Figure 6 is a sprocket in section with chain in elevation winding upon it the pintle pins in section.

Figure 7 is a diagrammatic enlarged section through the pintle pin showing the outline of the aperture in the link with which it is related.

Figures 8 and 9 are diagrammatic showings illustrating the manner in which the double point articulation which is characteristic of my invention assists the tension in the chain to resist lateral deflection or thrash.

Figure 10 is similar to Fig. 3, but shows a modied form of chain wherein segmental liners are interposed between each pin and its 'associated links.

Figure 11 is a section of the chain shown in Fig. 10 with the pintle pin in elevation.

Figure 12 is a View similar to Fig. 10 showing the chain in front bend position.

Figure 13 is a View similar to Fig. 3 showing a modified form of chain wherein the pintle pin is rigidly mounted in one of the two links.

Figure 14 is a modied form wherein but a single liner is used with each pin.

Like parts are indicated by like characters throughout the specification and drawings.

My invention is illustrated for the sake of convenience only in connection with a silent chain and so far as we are here concerned the specic relationship between the chain link teeth and the sprocket and the dimensions of chain, sprocket, pintle pin and the like is immaterial and shown merely for the purpose of illustration. j

The chain is made up of a series of overlapping toothed chain links A, A1. Theyv are joined in articulating relation with one another by means of a series of noncircular pins A2, which preferably extend clear across the width of the chain and hold the assembled links together, so Ythat the chain may wind onto or off of a sprocket wheel, the chain teeth engaging the sprocket wheel teeth in the usual manner.

, The selection of a silent chain of the particular type here selected is for purposes of illustration only. The untoothed links shown in Figure 1 are merely guide links adapted to maintain the chain in alignment on the sprocket wheels and form no part of my invention. A3 is a sprocket about whichV the chain is wound.

Referring now to the coss section of the pintle pin shown in Figure '7, the line z-z is the minor and the line m-yl the major axis. The line z-z is generally in alignment with the line of normal chain tension between the sprockets. It will be understood that the cross section of the pintle pin is the same throughout its entire length and the pin and hole relationship shown in the drawings and which I am about to describe is simply a satisfactory arbitrarily selectedrrelationship, it being entirely possible to accomplish the purpose which I desire to accomplish in many other ways and by many different designs. j Y

The distance between the pointsa-b which are preferably equidistant from intersection of the lines 931-1311 and 2 2 is arbitrarily selected. Then with the point ct as a center, the arc y,y1-y3and with the point b as a center the arc :c-m1-:n3 are described. These arcs Vare so laid out that Y pintle pin so formedis in relationship withlalink the distance y-yl along the curve` is the same as the distance 'y1-@ and the distance x-xl along` the curveis the same as the distance :r1- x3 and the distance y-yl along Vthe curve is the same as the distance :zr-ns1. The length of these arcs and `their radii have been so selected that lines e--yV and zV-y are tangent to the arc Yy--yl--g/Kand the lines zx and .Q -.r3 are tangent to the arc do .the lines y3-e and :r3-z torform obtuse angles.

The reason for providing this obtuse angular relay.

tionship between these lines is that ,when the aperture similarly formed as will hereinafter -appear then tension on the chainKin that part of it between the sprockets tends to cause the pintle pin to seat in a central positiony in the hole thereby reducing any tendency toward friction properly centering the pin and giving a relatively wide area of link pin contact. l

As the chain winds ontoY a'wheel or sprocket, irontbend `must take place and depending upon 'the' chain pitch, the chain tooth design and the sizeof `sprocket over which the chain is to run, the `designer can fix theV maximum angle of front bend at each chain pintle.V In this case c is the angle of frontbend and in order that the chain be not too stiff and may have a certain amount of flexibility itis desirable to design Yfor a certain smaller amountof back bend and the angle dis Y the angle of back bend selectedfor eachpintle.

VUsing, the point y1 as a center, an arc is struck .with radius equal to the distance yl-a to intersect tance r1-,b is laid ofi to `intersect the line a,-2. VThat point of intersection is used as a center for an arc in continuationof the arcv .1s-x1, thesetwo arcs extending each of them to the right of Figure 7; The lengths of these arcs are selected such that tangents extending from their termini will Y. intersect at an angle the same as the angle The purpose of doing this is'to define jthe size Y and shape of the apertures such that the pin may rotate in the aperture about either one of the centers a orb and suchthat the rotation ofthe pin about the center a may be limited to the angle c, and the rotation pin about the center b mayL be limited to the angle d. K Suflicient'clearance is obtained in the design above pointed out because the extension arcs generally in prolongation of the arcs 11j-y1 and -:L'l respectivelyare on thesa'me radius as the arcs which they prolong although the vcenter about which they are formed is laterally displaced to compensate for the rotation of the `pintle in the hole, hence rotation about either one of these center points is brought to a halt when vthe pin engages the wall of the aperture on the side Vopposed to its normal position as shown in Figure 7.

right. 'I'his holds the link and'pintle in the `rela` tive position shown in Fig. 7, the left hand side of` the link aperture seated in the left hand side of the hole in the pintle, therebeing an irregular shaped clearance between therighthan'd. sides of each. If the pintle pin rotates about the :cente'rfa "7'5 inthe link in a counter-clockwise"direction, 'the accetti surface on the left hand side ofthe link and aperture will separateV and that separation will continue to a maximum at the time when the right hand side of the pin engages the right handside' concentric with the center of rotation'a and because the arc .1J-#y1 coincides Yboth in the pinvand `in the 1ink,the link may 'rotate'pivotwise about the center a` and because of the way in which the aperture walls are laid out on theV right hand side,

1o i 'this rotation -is not interfered with by contact between the pin along the arc y-y3 and the wall oi tively stopped. The limiting contacting surfaces when they come together will come together along Y generally normal lines Vsono friction or rubbing will take place between the flat surfaces, hence no wearing and no pitch change.` Y

The opposite situation prevails vif the pin rotates inaclockwise direction about Ythe center b only inKthis case theV bearing is along the line :r-xl--zc3 and the upper portion of the pin moves toward the right Vuntil there is no contact Aalong the line y-Ky1 but there is contact in the vicinity of the -line or arc yl-yL-y? which contactkv prevents further angular displacement of the pintle with respect tothe link. In connection with either of these two Amotions it will be noted that the tension in the chain whichis appliedalong the line z-e and which tends-to keep the surfaceslha, a: on the left hand side of the pinin engage ment with and centered in the surfaces y, z, :c on

the left hand side of the link aperture vwill resist rotation of the pin abouteither therpivot points a or b and the lever arm through which this ten-` sion works will bea lever arm equal to one-half the distance aK-b. Y'Ihe parts in the position shown in Fig. 7 being in a position of stability, any motion tending to rotate the pin about the center a or b tends to bodily displace the pin breaking the contactat e, y, such force being instantly K resisted.Y Y

It is 'of course known that when a violin string K is plucked it isdeiiecteclv outside of the line of tensionand the tension in the string ktends to return the string itself to a position in alignment between its two supporting points. That isrexact- Y Y ly what takes place in connection with my chain, but because deiiectionof thechain to the right or to the left as the case maybe compels clockwise or counter-clockwise rotation of Vthev pintle there is this tendency to return each articulated pair of links back to normal and `this tendency K is illustrated as a tendency applied'at the points b3, b4 etc. in Fig. 9.

Referringto Figure 8, thepoints a, through a1 'to a6, show the 'positions of the pintle pivot c,

*as the chain travels fin a `straight line direction Ywithoutthrash or deflection Vunder tension 1from `one sprocket to the other. It makes no 'differ- K 'ence `whether geometric line of tension passes throughthese points or not, thatline will be some- Where naar them andswill be parallelV Withihe,

linejoining these poin ts.,` Now if as shownoin Figure 9, ,the chain tendsA tov deflect downwardly,

relatienship shown inFigure 7, and toucause the pintleLand `linkito rotatewith respect to one another, aboutgthe `point intending to cause the right hand side' Yof v the pintle to approach Ythe righthandsidepi the hole in the link. Now if the distancethrough which this deilection takes placeisshQWnat g, vit will be obviousY that the leverarm through .wl1ich force is applied tend-- ingto resist this, will be as Vmuch greater thanl g,

asis therdistance between the intersection of the l lines 2 2 and .r1-y1 and the pivot pointue-auses ,l

theJever., arm above referred to tending to resist separation of the surface -'fz-y is equalto the distance between thepivot point a, and the intersection point vand that distance is represented by the value j. The design, of the chain is such that y,at all times the leverarm `f is greater than' ,thedistance g even up to the point that when the link and pin have rotated through the angle c, at which -rotation stops, Y

Chain design is complicated by the fact that l the chain is made in very large quantities and commercially must be sold for many different purposes, so ordinarilyV chain is not designed for onespecicuse only and all design must be a compromise.

As far as resistance to thrash is concerned, the greaterthe distance .ef-b, the more effective becomes thevthrash preventing means, but as the distance a-b is increased thevradii of the arcs 1, y1, g3 and :12, :01, x3 are decreased because in this case the radius would no longer be the distance .eL-b, but a distance equal to the distance from the point a or b to the end of the major axis of the cross sectional area of the' pintle pin and the shorter this radius, the thinnerbecomes the pintle pin.V A point can be reached, of course, where tthe pintle pin becomes so thin that it is not strongA enough ,tocarry-the load. On .the other hand, if `the distance a-b is decreasedwe tend to approach theeonventionaltype of chain with a cylindrical pintle and the shorter the distance a-b, the stronger the chain, but the less the resistance to chain thrash. The chain designer is therefore compelled to select more or less arbitrarily the distance a-b and lit it into the chain with reference to his link tooth design, his sprocket tooth design and the other features of the chain selected by him for the purpose for which the chain is to be used.

The modifications shown in Figures l to 13 inclusive merely illustrate different forms of chain with which my invention may be used. For instance, in Figures 9, and l1, link b is provided with a pintle pin b'. The aperture in the link is divided into two equal segments by the lugs b2 and b3, the outer segment having a liner b4 tightly held therein free to travel in the Wider space between the lugs b2 b3 of the adjacent links. In this case the liner tends to tie all the links extending in one direction together, The relationship7 however, between the pin and liner and between the liner and link being in effect as that shown in the preferred form. In Figure 12 a further modicaton is shown. In this case the pin 112 being fitted in one length gets its play or freedom to rock from articulation and make its force felt to prevent thrash especially in the adiaentflinls the. risul? beiuaxud in .ihailsfi to the, aperture @23 inthe aperture w21,-

In the modified form shown ineFigure 13 every alternate link near j contains opposed segmental bushings. 1f? f3, the; links f having irregular .Shaped apariureaf* f5 to permit movement. 0i ihaluush-v ings f2 j? associated with the pins j i so that1 the` articulationnd thethrashresisting characteristics arethe same but the bushing rathernthan hand end of the link (L22 willbe free to oscillate in .the A.a .pe rture.o23 in the right hand end ofthe linkugkfthe aperture CL2? andthe link 122 being` the linkandpin itself takes whatever wear thereA All these ,alternate formsV and vmanywothers which might be shown, maybe applied to silent chai nroller chainbloc k chain orother chain, but allA such forms have the common characteristic,

that ,the,articulating relation between the link Y andthe lpin 4is one-,which 'is associated with a pair of articulationpoints o r lines (if We consider the whole chain)-- sucharticulating points being Y spaceda'greater or less distance apartand being located ,on` opposed sidesV of the normal line of f tension of thechain, sothat as chainthrash corn- Inences. and chain links uare ,given a relatively angular movement atpoints removed from the sprocket, the tension Vin thechainv is caused to y,

, immediately make itselfnfeltthrough the lever arm representing the distance from theline'of tensioni-.to oneother of the articulation points.

In a sensethe eifect is much like that of the old e fashioned rocking chair. The pintle is so lformed that it cannot rotate abouta central axis with respect to the link, the irregular shape of the@ pintle and the hole-inA the link making that irnpossible, .Any angular displacement of the link andthe pintle must take place either with the link rotatingabout one or the Vother of its centers of rotation and whichever center servesas the fulcrum rotation tends to cause a separation of the surfaces, x-a-y, which separation is resisted by the tension in the chain, just as is the case in the old; fashioned rocking chair Where there is a flat `spot on the rocker.

`I claim: k

1. A power .transmission chain comprisingv a plurality 1 of articulated ai).ertuiudA tension irraggia-k bers, one piece pivot pins upon which they articulate, the major axis of the aperture in the plane` y of the tension member intersecting the neutral axis of the chain, the minor axis being generally parallel with the neutral axis of the chain, the aperture being bounded at each end by a curved line, each side being formed along two straight Ylines inclined to each other and tangent to the aperture being bounded at each end by a curved line, each side being formed along two straight lines inclined to each other and tangent to the curved ends, the opposed faces of the pivot pins conforming generally to the opposed bounding surface of contour of the aperturesand free to rock and slide in the apertures the tension line of the chain passing between and never intersecting either of the curved lines bounding'the aperture. e f

3. A chain comprising a plurality of articulating links apertured at their ends, the apertures on successive links being in line, a pivot pinrpassving through said apertures and joining the` links to form a chain, theapertures being longer Yin v a direction perpendicular to the chain than in a Y directionparallel with it, the ends of the aper'- tures being bounded by cylindrical surfaces Vand Y joined by tangent plane surfaces, which plane surfaces generally intersect the axis of the chain, i

the opposed faces of the pivot pins .conforming generally to the opposed bounding surfaces of the contour of the apertures and free to rock and slide in the apertures. Y

4. A chain comprising a plurality of articulat- Y ing links aperturedat their ends, the apertures on successive links being in line, apivot pin passing throughsaid apertures and joining the links torform a chain, the Yapertures being longer inV `a direction perpendicular to the chain than' in a' Y Ydirection parallel with it, the ends of theape'rtures being Vbounded by cylindrical surfaces and joined' by tangent plane surfaces,` which plane; surfaces generally intersect the axis of the chain, if

the pin conforming generally to the shape of the aperture adapted Vto rock slightly within the aperture to vlimit relative angular displacement of the links. Y Y i 5. A chain comprising a plurality of articulatingV apertured sprocket engaging members, one piece pvot pins joining them and upon Which Vthey articulate, the apertures being bounded at their :ends byopposedcurved ends and at their sides by inclined straight Walls, the pinhaving Straight side surfaces adapted to come into flat- Wise Contact with the straight walls'bounding the z. 2,669,591 by straight Walls inclined to one another, each Wall being tangentV to the curved wall adjacent thereto, the pin conforming generally to the shape ofthe aperture and adapted to rotate slightly therein the tension'line of the chain pass-- ing between and never intersectingeither of the curved lines bounding the aperture. Y f

'1.111 a Chaimapmrlity ofarticuiated perfo;V

rate links, a pivot pin 'upon'whichthey are articulated, the pin having at either kside of the line -of rtension of the chain opposed curved surfaces described about spaced centers, bearing surfaces generally tangent to said opposed surfaces,rthe

apertures of the links Vhaving similar bearing sur-` l' faces in opposition to the opposed bearing surfaces on the pintle, and curved surfaces joining them upon which the curved surfaces on the pin may travel.

8. In a chain, a pivot pin having a plurality of ycurved and flat bounding surfaces, a linkhaving an aperture in which the pin is rockably mounted and which is bounded by a plurality of curvedk and flat surfaces, the curved surfaces on pin and link being in opposition to and adapted to engage one another only, theiat surfaces on pin sind link being in opposition to and adapted to engage one `another only, the relationship between the ff flat and curved'surfaces! beingVV such that as the pin rotatesin Vthe link with the curved surfacesV of one pair in opposition to one another, oneV pair and link causes slidingV movement with respect to the second pair of curved surfaces as Vthe rst. pair of curved surfaces separate one from the other until the second pair of flat surfaces'come in ContactV with one another. Y Y

9. A chain comprising a plurality of articulating links apertured at their ends, the apertures on successive links being inline, a pivot pin pass'- ing through said apertures and joining the links to form a chain, the apertures being longer-iria direction perpendicular toY the chain Vthan in a direction Yparallel with it,'the ends of the` apertures being rounded by cylindrical surfaces and joined byvtangent surfaces, which tangent surfaces generally intersect the axis of the chain. Y HAROLD S. PIERCE.

j of opposed fiat surfaces may approach until they;`

contact, whereupon further rotation of the pin 

